Four Bar Rear Suspension for a Bicycle

ABSTRACT

A bicycle frame is adapted to provide suspension to a human user. The bicycle frame has a top tube and down tube connected to a head tube. A seat tube, fixed to the top tube and down tube connects to the bottom bracket. A chain stay is rotatably coupled to the seat tube at a chain stay pivot. A seat stay is rotatably coupled to the seat tube at a seat stay pivot. An upper shock mount is attached to a distal end of the seat stay forward of the seat stay pivot. A lower shock mount is attached to the chain stay rearward of the seat stay pivot. A shock is connected to the upper shock mount and the lower shock mount passing the seat tube from forward to rearward. A rear axle plate is attached to the seat stay and the chain stay and configured to accommodate a rear axle.

RELATED APPLICATIONS

This application is continuation of U.S. National Stage application Ser.No. 15/778,530 filed May 23, 2018, now U.S. Pat. No. 10,737,742 issuedAug. 11, 2020, claiming priority under 35 U.S.C. 371 from InternationalPatent Application No. PCT/US2016/63160 filed Nov. 21, 2016, whichclaims the benefit of priority from Provisional Patent Application No.62/259,204 filed Nov. 24, 2015, the entire contents of which are hereinincorporated by reference.

FIELD OF THE INVENTION

The present invention provides a bicycle frame. Specifically, thepresent invention pertains to bicycle frame systems for mountain and/oroff road bicycles wherein the frame is comprised of a suspension systemand floating brake design resulting in improved traction of the rearwheel during off road conditions and during braking.

BACKGROUND OF THE INVENTION

Suspension systems for bicycles suffer from a number of performanceproblems. For example, when riding during off road conditions, there maybe a loss of rear wheel traction. Similarly, during off road conditions,there may be a loss of rear wheel suspension when braking.

Improper force management of bumps and braking forces may result andcause a bicycle to come off the ground during off road trail riding.Manufacturing misalignments may cause binding conditions within thesuspension and linkage locations that are far removed from the rear axleand can promote binding in the suspension assembly during operation.

In light of the above, it is an object of the present invention toprovide the desired features described herein in addition to addressingthe performance problems of existing suspension systems.

SUMMARY OF THE INVENTION

The bicycle suspension system of the present invention is an improvementover the rear suspension systems known in the prior art. The suspensionsystem provides improved bicycle control for both off road and trailconditions by identifying the pivot locations or zones, placing theshock onto the primary moving structural members of the suspension andby simplifying and/or reducing the number of parts required for thefloating brake mount.

The combination of pivot locations, shock attachment locations and brakemounting bracket simplification make up the bicycle rear suspensionsystem. The system parameters and enhancements aim to improve suspensionsensitivity and neutralize braking induced suspension compression duringriding for improved rider control. The subsequent detailed descriptiondiscloses the three primary elements (structure and pivots, shockmounting, and brake mounting) of the novel design which comprise thesystem.

One object of the present invention is to provide a bicycle frame systemwherein rearward movement of the axle/wheel during bump interactionresults in the wheel engaging the ground longer by traveling with thebump instead of hopping over the bump, thereby increasing tireinteraction/adherence to the ground.

It is another object of the present invention to provide a bicycle framesystem having a shock that mounts to the seat stay and chain stay fordirect shock interaction and proper force transfer to said shock withoutframe flexure or binding. The frame suspension system transfers movementdirectly to the shock for better sensitivity that leads to improved tireadherence to the ground.

It is yet another object of the present invention to provide a pivotingbrake mount that enables the brake to travel with the rear wheel andtransfer forces away from the direction of suspension travel instead ofadding to the bump forces and prematurely loading the suspension toshock limits (this causes suspensions to firm up and no longer absorbbumps).

It is still another object of the present invention to provide a counterrotation of the rear wheel during braking to reduce chain growth causedby suspension movement. Typically, chain growth results in rider pedalfeedback and suspension compression retarding.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, and in which:

FIG. 1 illustrates the front triangle of the present invention.

FIG. 2 illustrates the brake bracket of the present invention.

FIG. 3 illustrates the forward brake mount bushing of the presentinvention.

FIG. 4 illustrates a close-up of the brake bracket assembly.

FIG. 5 illustrates an alternative view of the rear frame assembly of thepresent invention.

FIG. 6 illustrates a graph of the rear axle path as it travels throughthe fore aft and vertical directions.

FIG. 7 illustrates a visual representation of the graph in FIG. 6showing the axle path of the present invention.

The invention can be better visualized by turning now to the followingexamples.

DETAILED DESCRIPTION OF THE INVENTION

A bicycle frame 10 adapted to provide suspension to a human user isshown in FIG. 1. The bicycle frame 10 has a head tube 1 that isconfigured to hold handle bars (not shown). A top tube 2 and down tube17, or a monocoque structure, attaches to a head tube 1 and seat tube 3.The seat tube 3 and down tube 17 also attach to a bottom bracket 16configured to hold the cranks (not shown) and pedals (not shown). Thecombination of head tube 1, top tube 2, down tube 17, seat tube 3 andbottom bracket 16 make up what is defined as a rigid front triangle. Achain stay 15 is rotatably coupled to the seat tube 3 at a first chainstay pivot 8.

In an alternative embodiment, the chain stay 15 may be rotatably coupleto the down tube 17. A seat stay 6 is rotatably coupled to the seat tube3 at a seat stay pivot 5. In an alternative embodiment, the seat stay 6may be rotatably coupled to the top tube 2. An upper shock mount 4 isattached to a distal end of the seat stay 6 forward of the seat staypivot 5. A lower shock mount 9 is attached to the chain stay 15 rearwardof the first chain stay pivot 8.

In an alternative configuration, the lower shock mount 9 is attachedforward of the first chain stay pivot 8 or at the first chain stay pivot8. A shock 7 is connected to the upper shock mount 4 and the lower shockmount 9 passing the seat tube 3 from forward to rearward. If the lowershock mount 9 is positioned in the alternative configuration, the shock7 may not pass the seat tube 3 from forward to rearward. Rear axleplates 12 are attached to the seat stay 6 and the chain stay 15rotatably at points 11 and 14 and configured to accommodate a rear axle13. The axle plate pivot points should be no further than 300 mm awayfrom the rear axle centerline.

The frame 10 has primary structural members and pivots that enable thesuspension to move. The pivot locations of the four bar design of thepresent invention are critical for determining and managing the rearaxle path and its association to leverage ratio, chain growth/pedalkickback, pedal induced compression, and brake induced compression. Whenthe suspension encounters a bump, the axle 13, axle plates 12, seat stay6, and chain stay 15 rotate in an upward direction about the fronttriangle pivoting around the four main pivots (5,8,11,14) until the bumpforce is absorbed by the shock 7 at which point the suspension isreturned to the start position by shock forces.

The shock 7 in the present invention is repositioned from a fronttriangle mounting configuration as described in the prior art to themoving structural members of the rear suspension (the seat stay 6 andchain stay 15), as described herein. The shock 7 consists of acompression type shock in order to support the present invention insteadof a pull type as commonly used. The shock 7 is positioned forward ofthe seat stay pivot 5 at the front of the triangle and rearward of thesecond chain stay pivot 8 which is positioned above the bottom bracket16. As the suspension rotates upward about the four main pivots(5,8,11,14) the shock 7 is compressed by the seat stay 6 pushingdownward and the chain stay 15 pushing upward. The location of the shock7 and mounts with respect to the chain stay 15 and seat stay 6 arevisualized in FIG. 1. By moving the shock 7 from a single structural armactuation to the two structural arm configuration, all of the bumpforces encountered by the rear suspension are channeled to the bumpmanagement device instead of losing forces to frame/system flexure orshock binding (moving structural member loading off axis to a fixedfront triangle mounted shock) resulting in a more reactive suspensionand ultimately increased control to the rider.

The mounting of the shock to two moving members from one moving memberalso distributes the forces evenly, enabling lighter, more efficient(weight savings) structural members (seat stay and chain stay). This newmounting condition creates a more responsive suspension and ultimatelyimproves the control of the bicycle.

With regard to FIG. 2, shown is the brake bracket 20 of the presentinvention. With two pivots (11,14) in close proximity of the rear axle13, a moving brake bracket 20 was contemplated. Without a moving brakebracket, the rear wheel will spin backwards and pull on the chaincausing large pedal kickback during braking conditions where there issuspension travel. The brake bracket 20 must pivot around the rear axle13 while remaining firmly located during all suspension movements. As aresult, the brake bracket 20 of the present invention was developedwhere the rearward portion rotates around a boss on the axle plate 12 bywhich the rear axle 13 passes through. Rear axle bushings 23 (orbearings) are pressed into the brake bracket 20 for smooth rotation andtranslation, and the brake bracket 20 is sandwiched between the rearwheel and the axle plate 12 to retain axial positioning duringsuspension movement. The design of the present invention allows for rearwheel assembly/disassembly without the need for brake readjustment.

With regard to FIG. 3, shown is a custom forward brake mount bushing 30of the present invention. The forward portion of the bracket, as can beseen in FIG. 2, must now provide for translation and rotation to ensurepositional accuracy. This is accomplished by a single mount to the chainstay (not shown) that slides in a slot (24 shown in FIG. 2) and alsorotates through the use of bushings 30. The bushing 30 is furthercomprised of a rotating mount hole 32 surrounded by top and bottomsliding slot surfaces 31 positioned centrally in relation to a dustshield 33. The brake bracket and bushing 30 combination is of amplewidth to support locating needs through the suspension travel and stillkeep the brake in proper position.

The brake bracket 22 and bushing 30 are shown assembled in FIG. 4. Theconfiguration of the present invention results is a brake bracket 22that not only holds position, but more importantly, transmits thebraking forces away from the direction of suspension movement andeliminates brake induced suspension compression. A redirection of forcesis accomplished by angling the bracket so that the tangential brakingforce is directed through the chain stay 15 to the main frame during thesuspension movement. One additional benefit of the brake brackettranslation that should be noted is that during suspension movementwhile braking, the rear wheel rotates forward to oppose chain growthotherwise known as pedal kickback. An axle plate boss 43 having the rearaxle 13 pass through it is designed to enable rotation of the brakebracket 22 around the axle plate boss 43 during suspension movement. Thebrake bracket 22 further allows for attaching the chain stay 15 atmounting bolt 44 through rotation and translation slot 24 (not shown)while enabling movement during suspension travel. In an alternativeconfiguration, the brake bracket forward mount 44 may be attached to theseat stay 6 and achieve similar results of force transfer during brakingwith proper system design. The described brake bracket 22 is an integralpart of the defined improvements to the bicycle suspension system of thepresent invention. In an alternative embodiment, the brake bracket 22may be used with a variety of suspension systems proving similar forcetransfer and counter rotation benefits.

With regard to FIG. 5, shown is an alternative view of the frame of thepresent invention having both sides of the seat stay 6. Turning to thecomponents in more detail, a left side of seat stay 6 and a right sideof seat stay 53 pass on either side of the seat tube 3 and a cross brace(not shown) holds the first seat stay 6 and the second seat stay 53together at the seat tube 3. A first axle plate 12 and a second axleplate 55 are used to attach the left seat stay 6 and right seat stay 53,respectively, to the rear axle 13. A brake caliper 52 can be attached toa brake bracket 22 which is further attached to the first axle plate 12.

With regard to FIG. 6, shown is a graphical representation (curved line)of the path of the rear axle as it moves through suspension travel inthe fore aft and vertical (rearward and negative x) directions. FIG. 7is a visual representation to accompany FIG. 6 showing the axle path asassociated with the present invention.

One embodiment of the present invention provides a bicycle frame forproviding increased suspension to a bicycle, the bicycle framecomprising:

-   -   a head tube,    -   a top tube,    -   a down tube,    -   a seat tube,    -   a chain stay,    -   a seat stay,    -   an upper shock mount,    -   a lower shock mount,    -   a shock,    -   a rear axle plate and    -   a brake bracket and bushing.

Another embodiment of the present invention provides a head tubeconfigured to hold a set of handle bars.

In another embodiment of the present invention there is provided the toptube and the down tube connected to the head tube.

A further embodiment of the present invention provides a seat tubeconnected to the top tube, the down tube and a bottom bracket whereinthe seat tube, top tube, down tube and bottom bracket form a rigid fronttriangle.

Still another embodiment of the present invention provides a chain stayrotatably coupled to the seat tube at a chain stay pivot.

Yet another embodiment of the present invention provides a seat stayrotatably couple to the seat tube at a seat stay pivot.

A further embodiment of the present invention provides an upper shockmount attached to a distal end of the seat stay forward of the seat staypivot.

In another embodiment of the present invention there is provided a lowershock mount attached to the chain stay rearward of the seat stay pivot.

Still another embodiment of the present invention provides a shockconnected to the upper shock mount and the lower shock mount passing theseat tube from forward to rearward.

Another embodiment of the present invention provides a rear axle plateattached to the seat stay and the chain stay and is configured toaccommodate a rear axle.

Yet another embodiment of the present invention provides a bicycle framehaving four distinct pivot points.

A further embodiment of the present invention provides the bicycle framedescribed further comprising a floating brake design.

It will be appreciated that details of the foregoing embodiments, givenfor purposes of illustration, are not to be construed as limiting thescope of this invention. Although several embodiments of this inventionhave been described in detail above, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention, which isdefined in the following claims and all equivalents thereto. Further, itis recognized that many embodiments may be conceived that do not achieveall of the advantages of some embodiments, particularly of the preferredembodiments, yet the absence of a particular advantage shall not beconstrued to necessarily mean that such an embodiment is outside thescope of the present invention.

What is claimed is:
 1. A bicycle frame for providing increasedsuspension to a bicycle, the bicycle frame comprising: a head tubeconfigured to hold a fork and set of handle bars; a top tube connectedto the head tube and a down tube; a seat tube connected to the top tube,the down tube and a bottom bracket; a chain stay; a seat stay; a shockpositioned between and connected to an upper shock mount and a lowershock mount; rear axle plates; a rear axle passing through the rear axleplate; and a brake bracket and bushing, wherein the brake bracket iscomprised of a single component having a forward translation androtational mount and a rearward rotational mount, wherein the forwardportion of the brake bracket is further comprised of a single mount thatslides in a slot and further rotates using a bushing, the bushingfurther comprising a rotating mount hole surrounded by top and bottomsliding slot surfaces positioned centrally in relation to a dust shieldmoving piece configured to pivot about the rear axle.
 2. The bicycleframe of claim 1, wherein the bicycle frame is further comprised of fourdistinct pivot points.
 3. The bicycle frame of claim 2, wherein the seattube, top tube, down tube and bottom bracket form a rigid fronttriangle.
 4. The bicycle frame of claim 2, wherein the chain stay isrotatably coupled to the seat tube at a chain stay pivot.
 5. The bicycleframe of claim 2, wherein the seat stay is rotatably coupled to the seattube at a seat stay pivot.
 6. The bicycle frame of claim 5, wherein anupper shock mount is attached to a distal end of the seat stay forwardof the seat stay pivot.
 7. The bicycle frame of claim 6, wherein thelower shock mount is attached to the chain stay rearward of the seatstay pivot via a link or links.
 8. The bicycle frame of claim 7, whereinthe shock is connected between the upper shock mount and the lower shockmount.
 9. The bicycle frame of claim 6, wherein the lower shock mount isattached to the chain stay forward or at the seat stay pivot.
 10. Thebicycle frame of claim 8, wherein a moving brake remains firmly locatedwhen the brake bracket pivots around the rear axle.
 11. The bicycleframe of claim 10, wherein the rear axle centerline is less than 300 mmfrom the axle plate pivot points.
 12. The bicycle frame of claim 8,wherein a moving brake remains firmly located when mounted to the axleplate and pivots around the axis of the rear axle.
 13. The bicycle framebrake bracket of claim 1, wherein the brake bracket is capable ofpivoting around the rear axle at a rearward position of the brakebracket.
 14. The bicycle frame brake bracket of claim 1, wherein thebrake bracket is positioned between a rear wheel and an axle plate. 15.A bicycle frame for providing increased suspension to a bicycle, thebicycle frame comprising: a head tube configured to hold a fork and setof handle bars; a top tube connected to the head tube and a down tube; aseat tube connected to the top tube, the down tube and a bottom bracket;a chain stay; a seat stay; a shock positioned between and connected toan upper shock mount and a lower shock mount; rear axle plates; a rearaxle passing through the rear axle plate; and a brake bracket andbushing, wherein the brake is rigidly attached to the axel plate.